Hybrid electric vehicles (HEVs) utilize a combination of an internal combustion engine with at least one electric motor to provide power to vehicle traction wheels. HEVs may be configured to shut down the engine under certain operating conditions and operate in an electric only mode. In such situations, the electric motor provides all of the power to propel the vehicle. The engine may subsequently be started in response to, for example, an increase in drive power demand or a decrease in battery state of charge.